Dielectric heating is a process in which a high-frequency alternating electric field or radio waves, or microwave electromagnetic radiation heats a dielectric material, such as water molecules. At higher frequencies, this heating is caused by molecular dipole rotation within the dielectric material, while at lower frequencies in conductive fluids, other mechanisms such as ion-drag are more important in generating thermal energy.
Microwave frequencies are typically applied for cooking food items and are considered undesirable for drying laundry articles because of the possible temporary runaway thermal effects associated with random application of the waves in a traditional microwave. Radiant heat applied to moving air is typically used for drying textile material.
Radio frequencies and their corresponding controlled and contained RF electronic fields (e-fields) have been used for drying of textile material. When applying an e-field to a wet article, such as a clothing material, the e-field may cause the water molecules within the e-field to dielectrically heat, generating thermal energy which is known to dry textile material more rapidly than radiant heat.